CdII -Organic Frameworks Fabricated with a N-Rich Ligand and Flexible Dicarboxylates: Structural Diversity and Multi-Responsive Luminescent Sensing for Toxic Anions and Ethylenediamine.

Three metal-organic frameworks {[Cd(L)(glu)]⋅3 H2 O}∞ (1), {[Cd2 (L)2 (adi)2 ]⋅5 H2 O}∞ (2) and {[Cd(L)(sub)]⋅3 H2 O⋅DMA }∞ (3) (L=pyridine-3,5-bis(5-azabenzimidazole), H2 glu=glutaric acid, H2 adi=adipic acid and H2 sub=suberic acid) were obtained under solvothermal conditions. Complex 1 shows a 2D (4,4) network constructing of Cd2 -glu and Cd-L chains. Complex 2 presents a 2-fold interpenetrating 3D framework with pcu topology. Complex 3 is a 3D framework with cds topology. Three complexes with versatile structures were obtained by changing aliphatic dicarboxylate ligands with different lengths based on a N-rich ligand. Moreover, the fluorescence measurements indicate that complex 1 is a good multifunctional chemosensor for the detection of Cr2 O7 2- and MnO4 - anions by fluorescence quenching effect, and ethylenediamine by fluorescence enhancement effect, with detection limits of 1.196 ppm, 0.551 ppm and 64.572 ppm, respectively. Both complexes 2 and 3 can selectively sense Cr2 O7 2- anion with detection limits of 1.126 ppm for 2 and 0.831 ppm for 3 by a fluorescence quenching effect.